That heavy cooper wire seems to be attached to the tank near the sender, its uninsulated but under a bit of foam and was under one of the screws of the sender.
New sender works fine as I tested it yesterday and just sprayed the crap out of the sender top with a CRC product. I sprayed this stuff on my helm seat track 4 months ago since it was very stiff - the tension adjuster knob is gone - 4 months later every time I accerate I acceralte in reverse to the back of the track - kinda like going to the carnaval
